Conventionally, there is known an LED light emitting device that uses three types of LED elements, i.e., red, green, and blue LED elements, to emit white light (Patent literature 1). However, the respective LED elements have different forward voltage drops (vf), i.e., the red LED element has a forward voltage drop of approximately 2.0 V, green LED element approximately 3.3 V, and blue LED element approximately 3.4 V, so that, to adjust amounts of currents applied to the respective LED elements to adjust a balance among light amounts, a complicated calculation process is required, and for this reason, there is a problem that controlling a color temperature of the white light is difficult.
Also, in such a conventional LED light emitting device, red light, green light, and blue light respectively emitted from the LED light emitting device are mixed outside the device to generate the white light, so that even in the case where, from a distance, recognition as the white light can be gained, as viewed from an extremely close distance, the white light is nothing more than being separately recognized as the red light, the green light, and the blue light. For this reason, in order to use such a conventional LED light emitting device as a white light source, a sufficient distance is required from the light source, and therefore the conventional LED light emitting device is inappropriate for a light source for irradiating a close place.
Such a problem is also recognized even in an LED light emitting device that separately uses red, green, and blue phosphors without combining them to form, in the same device, a red color light emitting part, a green color light emitting part, and a blue color light emitting part that are partitioned from one another.
Also, in any of the configurations, in the case of, outside a device, mixing respective single color light of red, green, and blue, which were once emitted outside the device, to generate white light, if a light amount of any of the color light is changed, a color temperature of the white light is also largely changed. For this reason, a lot-based variation or difference in deterioration rate among LED elements largely affects the color temperature of the resultant white light, and therefore it is not easy to control it, for example, an extremely fine adjustment or complicated calculation process is required. This means that in an LED light emitting device employing a configuration in which red light, green light, and blue light, which were once emitted outside the device, are mixed to generate white light, even in the case of attempting to finely adjust a color temperature of the white light, the color temperature is likely to be largely changed, and in such a type of LED light emitting device, controlling a color temperature of white light requires a complicated calculation process after all, and is not easy.